Inspection system and inspection method

ABSTRACT

According to one embodiment, an inspection system includes an illuminator, an imager, and a processor. The illuminator irradiates light into an interior of a hole. The imager acquires a first image by imaging the interior of the hole where the light is irradiated. The processor detecting a blockage of at least a portion of the hole based on a luminance of the hole inside the first image.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromJapanese Patent Application No. 2017-211303, filed on Oct. 31, 2017; theentire contents of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to an inspection systemand an inspection method.

BACKGROUND

An inspection system and an inspection method have been proposed thatuse a robot to inspect the gap between a rotor and a stator of agenerator. Many vent holes are provided in the rotor. A gas (a coolinggas) flows in the vent holes and suppresses a temperature increase ofthe rotor. In the case where a blockage occurs in at least a portion ofthe vent holes, the flow rate of the gas passing through the vent holesdecreases; and the temperature of the rotor increases. When thetemperature of the rotor increases, thermal expansion of membersincluded in the rotor occurs; and an abnormal vibration of the rotor,etc., may occur. Therefore, an inspection of the generator is performedto check for blockage of the vent holes. It is desirable to develop aninspection system and an inspection method to perform the inspectionmore accurately.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are perspective views illustrating the generator;

FIG. 2 is a perspective cross-sectional view illustrating the vent holevicinity of the rotor included in the generator;

FIG. 3 is a schematic view illustrating the configuration of theinspection system according to the embodiment;

FIG. 4 is a flowchart illustrating the inspection method according tothe inspection system according to the embodiment;

FIGS. 5A to 5C are drawings for describing the inspection systemaccording to the embodiment;

FIGS. 6A to 6C are drawings for describing the processing according tothe inspection system according to the embodiment;

FIGS. 7A and 7B are examples of other binary images obtained by theinspection system according to the embodiment;

FIG. 8 is a block diagram illustrating the configuration of aninspection system according to a second embodiment;

FIG. 9 is a perspective view illustrating the robot of the inspectionsystem according to the second embodiment;

FIG. 10 is a side view illustrating the robot of the inspection systemaccording to the second embodiment; and

FIG. 11 is a flowchart illustrating the operations of the inspectionsystem according to the second embodiment.

DETAILED DESCRIPTION

According to one embodiment, an inspection system includes anilluminator, an imager, and a processor. The illuminator irradiateslight into an interior of a hole. The imager acquires a first image byimaging the interior of the hole where the light is irradiated. Theprocessor detecting a blockage of at least a portion of the hole basedon a luminance of the hole inside the first image.

An inspection system according to an embodiment is used to inspect holesprovided in infrastructure equipment such as a generator, etc.Hereinbelow, the case will be described where the inspection systemaccording to the embodiment is used to inspect vent holes provided in arotor of a generator.

The schematic configuration of the generator will now be described.

FIGS. 1A and 1B are perspective views illustrating the generator.

A portion of the generator 1 is not illustrated in FIG. 1A to illustratethe internal structure of the generator 1. FIG. 1B is a perspective viewin which portion P1 of FIG. 1A is enlarged.

As illustrated in FIG. 1A, the generator 1 includes a stator 10 and arotor 20. The rotor 20 rotates with a rotation axis A1 at the center.The stator 10 is provided around the rotor 20. The direction from thestator 10 toward the rotor 20 is perpendicular to the rotation axis A1.

As illustrated in FIG. 1B, multiple vent holes 25 are provided in thesurface of the rotor 20. The multiple vent holes 25 are arranged alongan axial direction AD of the rotation axis A1 and a rotation direction Rof the rotor 20.

For example, the inspection system according to the embodiment inspectsthe rotor 20 in a state in which the rotor 20 is removed from the stator10. Or, as described below, the inspection system according to theembodiment may include a robot moving between the stator 10 and therotor 20. In such a case, the rotor 20 can be inspected in a state inwhich the rotor 20 is disposed on the inner side of the stator 10.

FIG. 2 is a perspective cross-sectional view illustrating the vent holevicinity of the rotor included in the generator.

As illustrated in FIG. 2, the rotor 20 includes a stacked body 21 and awedge (a fixing member) 22. The stacked body 21 includes multiple coils21 a and multiple insulating bodies 21 b. The multiple coils 21 a andthe multiple insulating bodies 21 b are provided alternately in a firstdirection D1 from the rotor 20 toward the stator 10. An example of thefirst direction D1 is shown in FIG. 2. The wedge 22 is provided on thestacked body 21 and fixes the stacked body 21. The wedge 22 is exposedat the surface of the rotor 20.

A first opening OP1 that pierces the stacked body 21 in the firstdirection D1 is provided in the stacked body 21. A second opening OP2that pierces the wedge 22 in the first direction D1 is provided in thewedge 22. The vent hole 25 is formed of the first opening OP1 and thesecond opening OP2 overlapping in the first direction D1.

A portion of the stacked body 21 overlaps the second opening OP2 in thefirst direction D1. In the example illustrated in FIG. 2, the stackedbody 21 includes a first portion 211 and a second portion 212overlapping the second opening OP2. The first portion 211 and the secondportion 212 are separated from each other. The first opening OP1 ispositioned between the first portion 211 and the second portion 212.

As an example, a length Le1 of the second opening OP2 in a directionperpendicular to the first direction D1 is 16 mm. A length Le2 of thefirst opening OP1 in this direction is 3 mm. A length Le3 of the firstopening OP1 in the first direction D1 is 150 mm.

FIG. 3 is a schematic view illustrating the configuration of theinspection system according to the embodiment.

As illustrated in FIG. 3, the inspection system 100 according to theembodiment includes an illuminator 70, an imager 80, and a processor 90.

The illuminator 70 irradiates light into the interior of the vent hole25. The imager 80 acquires a first image by imaging the interior of thevent hole 25 where the light is irradiated. The imager 80 transmits thefirst image to the processor 90. The processor 90 detects a blockage inat least a portion of the vent hole 25 based on the luminance of thevent hole 25 inside the first image. In other words, a constriction or ablockage of the vent hole 25 is detected. Hereinbelow, the blockage inat least a portion of the vent hole 25 is called an “abnormality” of thevent hole 25. Also, the state in which there is no constriction orblockage is called the “normal” state.

One device may include the illuminator 70, the imager 80, and theprocessor 90. One device may include the illuminator 70 and the imager80; and another device may include the processor 90. In such a case, thedevice that includes the illuminator 70 and the imager 80 is connectedby wired communication or wireless communication to the device includingthe processor 90.

As illustrated in FIG. 3, the illuminator 70 includes a light source 71,a lens 72, and a mirror 73.

The light source 71 is, for example, an LED (Light Emitting Diode). Thelight source 71 radiates light toward the mirror 73. The lens 72 isprovided between the light source 71 and the mirror 73. For example, thelight that is radiated from the light source 71 spreads in a radialconfiguration. The lens 72 is a plano-convex lens (e.g., a Fresnellens). The lens 72 refracts the radiated light to be aligned with thedirection from the light source 71 toward the mirror 73. Thereby,parallel light is emitted from the lens 72 toward the mirror 73. Thelight that is refracted by the lens 72 is reflected toward the vent hole25 by the mirror 73. The mirror 73 is positioned between the vent hole25 and the imager 80 when the vent hole 25 is imaged by the imager 80.The mirror 73 is, for example, a half mirror.

An inspection method according to the inspection system according to theembodiment will now be described in detail.

FIG. 4 is a flowchart illustrating the inspection method according tothe inspection system according to the embodiment.

FIGS. 5A to 5C are drawings for describing the inspection systemaccording to the embodiment.

FIGS. 5A to 5C illustrate images and data based on a state in whichthere is no abnormality in the vent hole 25.

The illuminator 70 irradiates the light toward the interior of the venthole 25 (step S101). The imager 80 acquires the first image by imagingthe vent hole 25 interior where the light is irradiated (step S102).FIG. 5A is an example of the first image.

As illustrated in FIG. 5A, the processor 90 detects an outer edge OP2 aof the second opening OP2 included in the first image. The outer edgeOP2 a is, for example, circular. The outer edge of the second openingOP2 lower end is detected in the example illustrated in FIG. 5A. Theprocessor 90 extracts the area surrounded with the outer edge OP2 a asan inspection area IA (step S103). For example, the processor 90extracts the area surrounded with the outer edge OP2 a as the inspectionarea IA by masking the area at the outer edge OP2 a periphery.

The processor 90 binarizes the inspection area IA (step S104). Thereby,a binary image is generated. By the binarization, the portions where theluminance is relatively high are converted into a first color; and theportions where the luminance is relatively low are converted into asecond color. The first color is different from the second color. Thecase will now be described where the first color is white and the secondcolor is black.

FIG. 5B illustrates the luminance at each position along line A-A′ ofFIG. 5A. From FIG. 5B, it can be seen that the luminance is relativelyhigh at the positions where the stacked body 21 is provided; and theluminance is relatively low at the position of the first opening OP1.Accordingly, in the binary image as illustrated in FIG. 5C, the stackedbody 21 is illustrated by white; and the first opening OP1 isillustrated by black.

The processor 90 detects the white particles from the binary image (stepS105). Specifically, the processor 90 detects a cluster of white pointshaving at least a preset surface area to be a particle.

The processor 90 inspects the abnormality of the vent hole 25 based onthe detected particles.

Specifically, the processor 90 executes the following step S106 to stepS110.

The processor 90 verifies whether or not the number of particlesincluded in the binary image matches a preset reference value (stepS106). When looking into the vent hole 25 in the example illustrated inFIG. 5A, the first portion 211 and the second portion 212 of the stackedbody 21 separated by the first opening OP1 are viewed. In such a case,the reference value is set to 2. In the case where there is anabnormality in the vent hole 25 (the first opening OP1), the number ofparticles may be different from the reference value. Accordingly, in thecase where the number of detected particles is different from thereference value, the processor 90 determines that there is anabnormality in the vent hole 25; and the inspection ends.

The processor 90 determines whether or not the position of a centroidCG1 of a first particle Pa1 is normal (step S107). For example, theprocessor 90 determines a center C1 of the outer edge OP2 a asillustrated in FIG. 5A. As illustrated in FIG. 5C, the processor 90 setsthe particle on one side of the center C1 to be the first particle Pa1and sets the other particle on the other side of the center C1 to be asecond particle Pa2. The first particle Pa1 corresponds to the firstportion 211 of the stacked body 21. The processor 90 calculates theposition of the centroid CG1 of the first particle Pa1. For example, asillustrated in FIG. 5C, the processor 90 calculates a first distance Di1between the centroid CG1 of the first particle Pa1 and the center C1. Inthe case where the first distance Di1 is not within a preset first range(a distance range), the processor 90 determines the position of thecentroid CG1 to be abnormal. In the case where it is determined that theposition of the centroid CG1 is abnormal, the processor 90 determinesthat there is an abnormality in the vent hole 25; and the inspectionends.

The processor 90 determines whether or not the position of a centroidCG2 of the second particle Pa2 is normal (step S108). The secondparticle Pa2 corresponds to the second portion 212 of the stacked body21. This determination method is similar to the determination method ofthe centroid CG1 of the first particle Pa1 described above. In otherwords, the processor 90 calculates a second distance Di2 between thecentroid CG2 of the second particle Pa2 and the center C1. In the casewhere the second distance Di2 is not within a preset second range, theprocessor 90 determines the position of the centroid CG2 to be abnormal.For example, the same values as the upper limit and the lower limit ofthe first range are respectively set as the upper limit and the lowerlimit of the second range.

The processor 90 determines whether or not the surface area of the firstparticle Pa1 is normal (step S109). For example, the processor 90calculates a first surface area of the first particle Pa1. In the casewhere the first surface area is not within a preset third range (asurface area range), the processor 90 determines the first surface areato be abnormal. In the case where it is determined that the firstsurface area of the first particle Pa1 is abnormal, the processor 90determines that there is an abnormality in the vent hole 25; and theinspection ends.

The processor 90 determines whether or not a second surface area of thesecond particle Pat is normal (step S110). This determination method issimilar to the determination method of the first surface area of thefirst particle Pa1 described above. In other words, the processor 90calculates the second surface area. In the case where the second surfacearea is not within a preset fourth range, the processor 90 determinesthe second surface area to be abnormal.

For example, in the case where there is an abnormality in the vent hole25, the sizes, the configurations, etc., of the particles change.Thereby, the centroids and the surface areas of the particles also maychange. Therefore, it can be verified whether or not the vent hole 25 isnormal by verifying whether or not the centroids and the surface areasof the particles are normal.

FIGS. 6A to 6C are drawings for describing the processing according tothe inspection system according to the embodiment.

FIGS. 6A to 6C illustrate images and data based on the state in whichthe vent hole is blocked.

FIG. 6A illustrates the first image in the state in which the firstopening OP1 is blocked due to shifting of the insulating body 21 b. FIG.6B illustrates the luminance at each point along line B-B′ of FIG. 6A.From FIG. 6A and FIG. 6B, it can be seen that an object that reflectsthe light exists between the first portion 211 and the second portion212 of the stacked body 21.

The binary image illustrated in FIG. 6C is obtained by binarizing thefirst image illustrated in FIG. 6A. In the example illustrated in FIG.6C, the processor 90 detects another particle Pa3 between the firstparticle Pa1 corresponding to the first portion 211 and the secondparticle Pat corresponding to the second portion 212. Accordingly, instep S106 of the flowchart illustrated in FIG. 4, the number ofparticles does not match the reference value; and the processor 90determines the vent hole 25 to be abnormal.

Effects of the embodiment will now be described. For example, there arecases where at least a portion of the vent hole 25 is blocked due toshifting of the insulating body 21 b. As illustrated in FIG. 2, thewidth (the length Le2) of the first opening OP1 is extremely narrowcompared to the length Le3 in the first direction D1 of the firstopening OP1. Therefore, particularly on the depthward side (the rotationaxis A1 side) of the vent hole 25, it is not easy to inspect anabnormality. Although the inspection of the vent hole 25 conventionallyhas been performed by viewing by a human as well, it has been difficultto perform an accurate inspection. A method also has been performed inwhich the vent hole 25 interior is viewed directly by inserting anendoscope into the vent hole 25; but much time is necessary for theinspection.

In the inspection system 100 and the inspection method according to theembodiment, the first image of the vent hole 25 interior where the lightis irradiated is acquired. The inventors discovered that the abnormalityof the vent hole 25 can be detected more accurately based on theluminance of the vent hole 25 inside the first image. In other words,according to the inspection system 100 according to the firstembodiment, the abnormality of the vent hole 25 can be detected moreaccurately. Also, according to the inspection system 100 according tothe first embodiment, because the abnormality is detected based on theimage, the time that is necessary for the inspection can be greatlyreduced compared to the case where an endoscope is used.

The illuminator 70 that has the configuration illustrated in FIG. 3 isused favorably in the inspection system 100 and the inspection methodaccording to the embodiment. According to the illuminator 70, the lightcan be irradiated toward the vent hole 25 along the first direction D1.Thereby, the depthward side of the vent hole 25 can be illuminatedsufficiently; and the abnormality on the depthward side of the vent hole25 can be detected more accurately.

As illustrated in FIGS. 5A to 5C, it is desirable to extract theinspection area IA on the inner side of the outer edge OP2 a and todetect the abnormality of the vent hole 25 based on the inspection areaIA. Thereby, objects that are unrelated to the vent hole 25 can beexcluded from the binary image. Accordingly, unintended particlesunrelated to the vent hole 25 can be prevented from being included inthe binary image; and the accuracy of the detection of the abnormalitycan be increased.

In the inspection method illustrated in FIG. 4, the abnormality of thevent hole 25 is detected based on the number of particles, the centroidsof the particles, and the surface areas of the particles. By inspectingusing these three parameters, the abnormality of the vent hole 25 can bedetected more accurately. However, in the inspection according to theinspection system 100 according to the embodiment, the abnormality ofthe vent hole 25 may be detected based on one or two of theseparameters. Even in such a case, the abnormality of the vent hole 25 canbe detected with sufficient accuracy.

In the determination of the abnormality relating to the centroid, forexample, the first distance Di1 is calculated based on coordinates inthe first image. The first range that is compared to the first distanceDi1 is set based on the coordinates in the first image.

Or, in step S107, the processor 90 may execute the following processingwhen calculating the centroid CG1. The processor 90 may calculate thefirst distance Di1 represented by a dimension in real space by using thedistance in the first image, the focal length of the imager 80, and thesize of the image sensor included in the imager 80. In such a case, theupper limit and the lower limit of the first range are represented bydimensions in real space.

As an example, the processor 90 calculates an angle of view θ in asecond direction perpendicular to the first direction D1 by using thefollowing Formula (1).

θ=2×arctan(L1×L2/2)   (1)

L1 is the focal length of the imager 80. L2 is the length in the seconddirection of the image sensor included in the imager 80. Based on thefollowing Formula (2), the processor 90 calculates an actual dimensionL4 in the second direction of the first image by using the angle of viewθ and a distance L3 between the lens of the imager 80 and the stackedbody 21.

L4=2×L3×tan(θ/2)   (2)

The processor 90 calculates the proportion of the distance (the numberof pixels) between the centroid CG1 and a center C2 in the first imageto the number of pixels in the second direction of the first image. Theprocessor 90 calculates the first distance Di1 represented by an actualdimension by multiplying the actual dimension L4 by the proportion.

According to this method, the first range that is based on the actualdistance can be preset by measuring the actual distance between thecenter of the vent hole 25 and the centroid of the first portion 211.Accordingly, it is unnecessary to set the first range based on thecoordinates in the first image. For example, a manager, the manufacturerof the inspection system 100, etc., can preset the first range bymeasuring the actual distance recited above; the work to be performed bythe worker inspecting the vent hole 25 can be reduced; and the burden ofthe worker can be relaxed.

Similarly, in step S108 as well, the second distance Di2 that isrepresented by a dimension in real space may be calculated. In such acase, the second range that is based on the actual distance is set bymeasuring the actual distance between the center of the vent hole 25 andthe centroid of the second portion 212.

In step S109, the processor 90 may calculate the first surface arearepresented by dimensions in real space. The first surface area iscalculated using the surface area of the first particle Pa1 in the firstimage, the focal length of the imager 80, and the size of the imagesensor included in the imager 80. Even in such a case, by measuring theactual surface area of the first portion 211 and by presetting the thirdrange based on the actual surface area, it is unnecessary to set thethird range based on the coordinates in the first image.

Similarly, in step S110 as well, the second surface area that isrepresented by dimensions in real space may be calculated; and thecomparison with the second surface area may be performed. In such acase, the actual surface area of the second portion 212 is measured; andthe fourth range is set based on the actual surface area.

By further investigating the technology recited above, the inventorsdiscovered the following.

In the case where the abnormality is detected based on the centroid ofthe particle, it is desirable for the lower limit of the first range tobe set to be not less than 0.6 times and not more than 0.8 times theactual distance between the first portion 211 and the center of thesecond opening OP2. It is desirable for the upper limit of the firstrange to be set to be not less than 1.2 times and not more than 1.4times this actual distance. Similarly, it is desirable for the lowerlimit and the upper limit of the second range compared to the seconddistance Di2 to be respectively set to be not less than 0.6 times andnot more than 0.8 times and not less than 1.2 times and not more than1.4 times the actual distance between the second portion 212 and thecenter of the second opening OP2.

In the case where the abnormality is detected based on the surface areaof the particle, it is desirable for the lower limit of the third rangecompared to the first surface area to be set to be not less than 0.90times and not more than 0.99 times the actual surface area of the firstportion 211. It is desirable for the upper limit of the third range tobe set to be not less than 1.01 times and not more than 1.10 times thisactual surface area. Similarly, it is desirable for the lower limit andthe upper limit of the fourth range compared to the second surface areato be respectively set to be not less than 0.90 times and not more than0.99 times and not less than 1.01 times and not more than 1.10 times theactual surface area of the second portion 212.

The inventors discovered that the detection accuracy of the inspectionsystem 100 and the inspection method according to the embodiment can beincreased by employing the ranges recited above.

Instead of steps S107 and S108, the processor 90 may calculate thecentroid of the entire particle. In such a case, the processor 90calculates the distance between the centroid of the entirety and thecenter C1 and determines the position of the centroid to be abnormal inthe case where the distance is not within a preset range.

Instead of steps S109 and S110, the processor 90 may calculate thesurface area of the entire particle. In such a case, the processor 90determines the surface area to be abnormal in the case where the surfacearea of the entirety is not within a preset range.

By these methods as well, the abnormality of the vent hole 25 can bedetected. However, there are cases where the centroid or the surfacearea of the entirety does not change even when the centroids or thesurface areas of the particles change. Accordingly, to increase thedetection accuracy of the abnormality of the vent hole 25, it isdesirable to determine the abnormality of the vent hole 25 based on thecentroids and the surface areas of the particles as illustrated in stepsS107 to S110.

The case is described in the example described above where two separatedlocations (the first portion 211 and the second portion 212) of thestacked body 21 are viewed through the second opening OP2. The inventionaccording to the embodiment is not limited to this example. Theinvention according to the embodiment is applicable also in the casewhere one location of the stacked body 21 is viewed or three or moreseparate locations of the stacked body 21 are viewed through the secondopening OP2. Even in such cases, based on the binary image, it ispossible to accurately verify whether or not the vent hole 25 is normalby verifying whether or not the number of particles, the centroid ofeach particle, and the surface area of each particle are normal.

FIGS. 7A and 7B are examples of other binary images obtained by theinspection system according to the embodiment.

FIGS. 7A and 7B illustrate a binary image in the case where two firstopenings OP1 are provided. In such a case, three mutually-separatedlocations of the stacked body 21 are viewed through the second openingOP2.

FIG. 7A illustrates a binary image based on the vent hole 25 in thenormal state. The three particles of the first particle Pa1, the secondparticle Pa2, and the third particle Pa3 are illustrated in the binaryimage of FIG. 7A. The third particle Pa3 corresponds to a third portion213 positioned between the first portion 211 and the second portion 212.

In the case where three particles are viewed in the state in which thevent hole 25 is normal, the reference value is set to 3 in the flowchartillustrated in FIG. 4. Also, for example, in the flowchart illustratedin FIG. 4, a step of determining whether or not the position of acentroid CG3 of the third particle Pa3 is normal and a step ofdetermining whether or not the surface area of the third particle Pa3 isnormal are further executed.

FIG. 7B illustrates a binary image based on a state in which a portionof the first opening OP1 between the second portion 212 and the thirdportion 213 is blocked. Compared to the binary image illustrated in FIG.7A, the surface area of the second particle Pa2 and the position of thesecond centroid CG2 have changed. In such a case, for example, theabnormality of the vent hole 25 is detected by determining the positionof the second centroid CG2 and the surface area of the second particlePa2 to be abnormal.

Thus, the specific detection method of the inspection system 100 and theinspection method according to the embodiment can be modifiedappropriately according to the appearance of the stacked body 21 throughthe second opening OP2.

Second Embodiment

FIG. 8 is a block diagram illustrating the configuration of aninspection system according to a second embodiment.

The inspection system 200 according to the second embodiment includes arobot 40. For example, as illustrated in FIG. 8, the robot 40 includesthe illuminator 70 and the imager 80. The robot 40 is connected by wiredcommunication or wireless communication to a terminal 91 including theprocessor 90. Or, the inspection system 200 according to the embodimentmay be realized by mounting the processor 90 in the robot 40.

The processor 90 detects the blockage in at least a portion of the venthole 25 based on the image acquired by the imager 80. Also, theprocessor 90 controls the operations of the robot 40.

FIG. 9 is a perspective view illustrating the robot of the inspectionsystem according to the second embodiment.

FIG. 10 is a side view illustrating the robot of the inspection systemaccording to the second embodiment.

As illustrated in FIG. 9, the robot 40 includes a base plate 41,multiple movement mechanisms 42, a suction mechanism 46, and aninspection unit 50.

For example, the base plate 41 is curved along the surface of the rotor20.

The robot 40 is moved in a frontward/rearward direction by the multiplemovement mechanisms 42. The multiple movement mechanisms 42 areseparated from each other in a width direction perpendicular to thefrontward/rearward direction. Each of the movement mechanisms 42includes a pair of pulleys 43 a and 43 b, a belt 44, and a motor 45.

The pulleys 43 a and 43 b are separated from each other in thefrontward/rearward direction. The belt 44 is laid over the pulleys 43 aand 43 b. The belt 44 is exposed on the lower surface side (the rotor 20side) of the base plate 41. For example, the motor 45 is linked to thepulley 43 a and rotates the pulley 43 a. By the rotation of the pulley43 a, the belt 44 is driven; and the robot 40 is moved. Also, themovement direction of the robot 40 can be changed by adjusting therotation amount of the pulley 43 a of one of the movement mechanisms 42and the rotation amount of the pulley 43 a of the other of the movementmechanisms 42.

The suction mechanism 46 is disposed at the side of the belt 44. Therobot 40 can be moved over the surface of the rotor 20 while being heldto the surface of the rotor 20 by the suction mechanism 46. For example,the suction mechanism 46 performs electrostatic attachment utilizingstatic electricity or performs vacuum attachment utilizing a pressuredifference. The robot 40 is moved or stopped on the surface of the rotor20 by adjusting the drive force due to the movement mechanisms 42 andthe holding force due to the suction mechanism 46.

The inspection unit 50 is provided on the base plate 41. For example,two inspection units 50 are provided and are separated from each otherin the width direction. The inspection unit 50 includes an air cylinder51, an arm 56, a travel guide described below, a sensor 61, and a sensor62.

The arm 56 is linked to a drive rod 52 of the air cylinder 51. Asillustrated in FIG. 10, one end portion of the arm 56 is movedvertically using the other end portion of the arm 56 as a fulcrum whenthe drive rod 52 is extended by the driving of the air cylinder 51. Apair of guide rollers 54 is separated from each other in thefrontward/rearward direction. A belt 55 is laid over the guide rollers54.

A not-illustrated air pipe is connected to the air cylinder 51. Anot-illustrated electrical cable is connected to the motor 45. Or, abattery may be mounted to the base plate 41; and the motor 45 may bedriven by the battery.

The sensors 61 and 62 are, for example, electric sensors, acousticsensors, mechanical sensors, etc. For example, the sensor 61 is anEL-CID (electro-magnetic core imperfection detector) sensor. The sensor62 includes a hammering-test hammer driver. For example, the robot 40performs the inspection of the generator 1 interior (the stator 10 andthe rotor 20) by using the sensors 61 and 62 while moving over thesurface of the rotor 20.

For example, as illustrated in FIG. 9 and FIG. 10, the illuminator 70and the imager 80 are provided at one end in the frontward/rearwarddirection of the robot 40. The vent hole 25 is positioned below therobot 40 in the case where the robot 40 moves over the surface of therotor 20. Therefore, the illuminator 70 irradiates the light below therobot 40; and the imager 80 images below the robot 40. In the case wherethe robot 40 moves over the surface of the stator 10, the vent hole 25is positioned above the robot 40. Therefore, the illuminator 70irradiates the light above the robot 40; and the imager 80 images abovethe robot 40.

Operations of the inspection system 200 according to the secondembodiment will now be described.

FIG. 11 is a flowchart illustrating the operations of the inspectionsystem according to the second embodiment.

First, the processor 90 determines whether or not there are uninspectedvent holes 25 (step S201). For example, the processor 90 refers to anot-illustrated memory storing the positions of the multiple vent holes25 to be inspected. The processor 90 acquires, from the memory, thepositions of the vent holes 25 for which the inspection has not yet beenexecuted. In the case where positions are acquired, it is determinedthat there are still vent holes 25 to be inspected. In the case where aposition is not acquired, it is determined that there are no vent holes25 to be inspected.

In the case where there are vent holes 25 for which the inspection hasnot yet been executed, the processor 90 acquires the current position ofthe robot 40 (step S202). For example, the processor 90 calculates thecurrent position of the robot 40 by using the initial position of therobot 40 and the movement distance of the robot 40.

The processor 90 determines whether or not the robot 40 has reached theinspection position (step S203). For example, the processor 90determines whether or not the current position of the robot 40 matchesthe position of the vent hole 25 to be inspected.

In the case where the robot 40 has not reached the inspection position,the processor 90 moves the robot 40 (step S204). In the case where therobot 40 has reached the inspection position, the processor 90determines whether or not the inspection area can be identified from theimage acquired by the imager 80 (step S205).

In the case where the inspection area cannot be identified, the flowreturns to step S202. Thereby, the identification of the inspection areais executed again based on the image acquired by the imager 80 and thecomparison between the current position of the robot 40 and theinspection position. In the case where the inspection area can beidentified, the inspection of the vent hole 25 is executed (step S206).The inspection of the vent hole 25 is executed according to steps S101to S110 of the flowchart illustrated in FIG. 4.

In the case where an abnormality is not detected in the inspection, theflow returns to step S201; and another vent hole 25 is inspected. In thecase where an abnormality is detected in the inspection, the processor90 executes a preset first operation (step S207). For example, in thefirst operation, the processor 90 transmits a notification to a presetemail address or terminal. The notification indicates that theabnormality of the vent hole 25 is detected.

In the case where there is no vent hole 25 to be inspected in step S201,the processor 90 executes a preset second operation (step S208). Forexample, in the second operation, the processor 90 moves the robot 40toward a prescribed position (outside the generator 1, etc.). Also, thedetermination result that there is no vent hole 25 to be inspected instep S201 indicates that all of the vent holes 25 are normal. Therefore,in the second operation, the processor 90 may transmit a notificationthat the vent holes 25 are normal to the preset email address orterminal.

The following operations may be executed instead of steps S201 to S205.

The imager 80 continuously images the surface of the rotor 20 while therobot 40 moves over the surface of the rotor 20. The processor 90 stopsthe robot 40 when an inspection area is identified from the imageacquired by the imager 80. Subsequently, the inspection of the vent hole25 is executed. In such a case, for example, it is determined that thereis no vent hole 25 to be inspected when the current position of therobot 40 reaches a prescribed region of the rotor 20.

According to the inspection system 200 according to the secondembodiment, the vent holes 25 can be inspected by moving the robot 40 inthe generator 1 interior. Therefore, it is unnecessary to remove therotor 20 from the stator 10; and the vent holes 25 can be inspectedefficiently.

The vent holes 25 may be inspected by moving the robot 40 over thesurface of the stator 10. More favorably, the robot 40 is moved over thesurface of the rotor 20. By moving the robot 40 over the surface of therotor 20, the illuminator 70 and the imager 80 can be positioned moreproximal to the vent hole 25; and the depthward side of the vent hole 25can be inspected more accurately.

The case is described in the examples described above where vent holesprovided in a generator are inspected by the inspection system and theinspection method according to the embodiments. The inspection systemand the inspection method according to the embodiments may be used toinspect holes other than those of a generator. For example, theinspection system and the inspection method according to the embodimentsmay be used to inspect the blockage of a vent hole of a building, etc.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel embodiments described hereinmay be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the embodimentsdescribed herein may be made without departing from the spirit of theinventions. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the invention. Moreover, above-mentioned embodiments can becombined mutually and can be carried out.

What is claimed is:
 1. An inspection system, comprising: an illuminatorirradiating light into an interior of a hole; an imager acquiring afirst image by imaging the interior of the hole where the light isirradiated; and a processor detecting a blockage of at least a portionof the hole based on a luminance of the hole inside the first image. 2.The system according to claim 1, wherein the illuminator includes alight source, a lens, and a mirror, the light source radiates lighttoward the mirror, the lens is provided between the light source and themirror and refracts the light to be aligned with a direction from thelight source toward the mirror, the mirror reflects the refracted lighttoward the hole, and the mirror is positioned between the hole and theimager when acquiring the first image.
 3. The system according to claim1, wherein the hole is provided in a rotor of a generator, the rotorincludes: a stacked body including a plurality of coils and a pluralityof insulating bodies provided alternately in a first direction, a firstopening piercing the stacked body in the first direction; and a fixingmember fixing the stacked body and being provided on the stacked body, asecond opening piercing the fixing member in the first direction, thehole is formed of the first opening and the second opening overlappingin the first direction, the stacked body includes a first portionoverlapping the second opening in the first direction, and the firstimage includes the first portion exposed through the second opening. 4.The system according to claim 3, wherein the processor generates abinary image using a first color and a second color by binarizing thefirst image, the first portion is displayed by the first color in thebinary image, the processor detects at least one particle of the firstcolor from the binary image, and the processor determines that theblockage has occurred in the case where a number of the particles isdifferent from a preset reference value.
 5. The system according toclaim 3, wherein the processor generates a binary image using a firstcolor and a second color by binarizing the first image, the firstportion is displayed by the first color in the binary image, based onthe binary image, the processor calculates a first distance between acenter of the second opening and a centroid of a first particlecorresponding to the first portion, and the processor determines thatthe blockage has occurred in the case where the first distance is notwithin a preset distance range.
 6. The system according to claim 3,wherein the processor generates a binary image using a first color and asecond color by binarizing the first image, the first portion isdisplayed by the first color in the binary image, based on the binaryimage, the processor calculates a first surface area of a first particlecorresponding to the first portion, and the processor determines thatthe blockage has occurred in the case where the first surface area isnot within a preset surface area range.
 7. The system according to claim3, wherein the processor generates a binary image using a first colorand a second color by binarizing the first image, the first portion isdisplayed by the first color in the binary image, the processor detectsat least one particle of the first color from the binary image, based onthe binary image, the processor calculates a first distance and a firstsurface area, the first distance being between a center of the secondopening and a centroid of a first particle corresponding to the firstportion, the first surface area being of the first particlecorresponding to the first portion, and the processor determines thatthe blockage has occurred in the case where a number of the particles isdifferent from a preset reference value, in the case where the firstdistance is not within a preset distance range, or in the case where thefirst surface area is not within a preset surface area range.
 8. Thesystem according to claim 5, wherein the first distance is calculatedusing a focal length of the imager, a size of an image sensor includedin the imager, and a distance between the centroid and the center in thebinary image, and the distance range is set based on an actual distancebetween a centroid of the first portion and the center of the secondopening.
 9. The system according to claim 8, wherein a lower limit ofthe distance range is set to be not less than 0.6 times and not morethan 0.8 times the actual distance, and an upper limit of the distancerange is set to be not less than 1.2 times and not more than 1.4 timesthe actual distance.
 10. The system according to claim 6, wherein thefirst surface area is calculated using a surface area of the firstparticle in the binary image, a focal length of the imager, and a sizeof an image sensor included in the imager, and the surface area range isset based on an actual surface area of the first portion.
 11. The systemaccording to claim 10, wherein a lower limit of the surface area rangeis set to be not less than 0.90 times and not more than 0.99 times theactual surface area, and an upper limit of the surface area range is setto be not less than 1.01 times and not more than 1.10 times the actualsurface area.
 12. The system according to claim 1, wherein the processordetects an outer edge of the second opening and detects the blockageusing an area on an inner side of the outer edge in the first image. 13.The system according to claim 1, further comprising a robot, theilluminator and the imager being provided in the robot.
 14. The systemaccording to claim 13, wherein the robot moves over the rotor.
 15. Aninspection method, comprising: irradiating light into an interior of ahole; acquiring a first image by imaging the interior of the hole wherethe light is irradiated; and detecting a blockage in at least a portionof the hole based on a luminance of the hole inside the first image. 16.The method according to claim 15, wherein the hole is provided in arotor of a generator, the rotor includes: a stacked body including aplurality of coils and a plurality of insulating bodies providedalternately in a first direction, a first opening piercing the stackedbody in the first direction; and a fixing member fixing the stacked bodyand being provided on the stacked body, a second opening piercing thefixing member in the first direction, the hole is formed of the firstopening and the second opening overlapping in the first direction, thestacked body includes a first portion overlapping the second opening inthe first direction, and the first image includes the first portionexposed through the second opening.
 17. The method according to claim16, comprising: generating a binary image using a first color and asecond color by binarizing the first image, the first portion beingdisplayed by the first color in the binary image; detecting at least oneparticle of the first color from the binary image; and determining thatthe blockage has occurred in the case where a number of the particles isdifferent from a preset reference value.
 18. The method according toclaim 16, comprising: generating a binary image using a first color anda second color by binarizing the first image, the first portion beingdisplayed by the first color in the binary image; based on the binaryimage, calculating a first distance between a center of the secondopening and a centroid of a first particle corresponding to the firstportion; and determining that the blockage has occurred in the casewhere the first distance is not within a preset range.
 19. The methodaccording to claim 16, comprising: generating a binary image using afirst color and a second color by binarizing the first image, the firstportion being displayed by the first color in the binary image; based onthe binary image, calculating a first surface area of a first particlecorresponding to the first portion; and determining that the blockagehas occurred in the case where the first surface area is not within apreset range.